I'm reasonably certain most would agree a cuckoo is not regarded as an accurate timepiece and normally I would agree. Now I'm not obsessed with an accurate cuckoo but a few mos. ago I began for some reason to track mine and see how close I could come. Surprised, I came close. REAL close but you know how difficult it is to move that leaf a mm. A tweak one direction and it's several minutes fast a week and vice versa. Well I had time on my hands and about an hour or so later, I borrowed the idea from a Wiener I have here. It's a micro adjustment applied to the stick. At less than a half ounce total for the entire pendulum it certainly won't take much weight to affect it. The micro is a teeny chunka lead friction fit to a steel guide. Currently I'm tweaking the leaf as previously and when I get into that final tweak range I'll turn to the micro and begin assessing it's effects Here: My astronomical cuckoo!